Process for forming powder pattern on light exposed layer having photosensitive diazonium salts

A process for forming a pattern of powder on a coating layer, which comprises a step of applying a photosensitive composition comprising a 4-(dimethylamino)benzenediazonium salt and at least one salt of o- and m-aminobenzenediazonium compounds selected from the group consisting of 4-alkoxy-5-(dimethylamino)benzenediazonium salt, 4-alkyl-5-(dimethylamino)benzenediazonium salt, 3-alkoxy-6-(dimethylamino)benzenediazonium salt, 4-alkoxy-6-(dimethylamino)benzenediazonium salt and 4-alkyl-5-(methylamino)benzenediazonium salt wherein the carbon atom number in alkyl groups and alkoxy groups in said salts is 2 or less, said composition containing 1-200% by weight of at least one of the salts of the o- and m-aminobenzenediazonium compounds on the basis of the 4-(dimethylamino)benzenediazonium salt, to a substrate thereby forming a thin layer, a step of subjecting the thin layer to patternwise light exposure to make the exposed portions of the layer sticky, and a step of contacting the light-exposed thin layer with powder particles, thereby depositing the powder particles to light-exposed portions of said thin layer.